Measurement speed has become an increasingly critical performance feature of modern network analyzers. High measurement speed may be so desirable in a manufacturing environment, that a user of a network analyzer may be willing to sacrifice measurement sensitivity when characterizing some device parameters, such as forward or reverse transmission parameters, if a corresponding increase in measurement speed could be gained. Alternatively, the user may choose to extract less than the full set of characterization parameters measured for a device under test (DUT) if a corresponding increase in measurement speed could be realized. In some measurement applications characterization of some device parameters, such as the reverse transmission scattering parameter S12, may not be necessary to verify performance of the DUT. However, due to measurement errors inherent within commercially available network analyzers, characterization of the forward transmission parameter of a DUT relies on not only measurement of the forward transmission characteristic of the DUT, but also on measurements of the reverse transmission characteristics and the forward and reverse reflection characteristics of the DUT. Thus, even in measurement applications in which only the forward transmission parameter of a device is sought, measurement speed can not be increased by simply omitting the measurements of the reverse transmission parameter and the reflection parameters of the DUT. Measurement speed is especially impacted when the DUT has high attenuation or high dynamic range, producing low-level signals at the network analyzer.
Presently available measurement methods indiscriminantly employ a narrow IF bandwidth in the network analyzer when measuring forward and reverse transmission and reflection characteristics of a high dynamic range DUT in an effort to improve measurement sensitivity. Because the narrow IF bandwidth retards the measurement response time of the network analyzer, measurement speed is unduly limited as a result of this indiscriminant use of the narrow IF bandwidth to measure the full set of transmission and reflection parameters of the DUT.
Accordingly, there is a need for a network analyzer measurement method that increases measurement speed for high dynamic range devices when the full set of device parameters are not sought or when measurement sensitivity can be sacrificed in the characterization of at least one of the device parameters.